Recently developed bioassay method of PIF and PRF will be used for the study of in-vitro release of prolactin regulating factors by the hypothalamus, their control by neurotransmitters, by the feedback effects of prolactin, and assays of biological fluids of patients with the galactorrhea-amenorrhea syndrome due to hyperprolactinemia. The mechanisms of biosynthesis of TRH, somatostatin, LH RH and the control of biosynthesis of these factors by neurotransmitters and hormones will also be studied. We will utilize whole hypothalamic fragments in organ superfusion systems, particulate fractions, and cell free systems. Studies will continue on secretion rate of hypothalamic hormones particularly TRH, LH RH and somatostatin. Problems of specificity require development of new methods for measuring these hormones in body fluids. Other studies include systematic analysis of phylogenetic and anatomical distribution of LH RH, TRH and somatostatin in representatives of vertebrate and non vertebrate species.